Hey there! Let us clarify that part: We want participants to either use what comes with RPG Maker MZ or something that they create themselves (either as a solo participant or as a team member). We made an exception for plugins because we didn't want to limit someone from doing something beyond just a turn-based RPG due to the functionality of the base engine without plugins. So for resources like music, art, etc, it has to either come with the engine or be something that you or a team member creates.
Please let us know if you have any other questions!